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On 19 February the US task unit 4.1.5 assumed escort responsibility with Gleaves-classdestroyersUSS Edison and Nicholson, Wickes-classdestroyersUSS Lea and Bernadou and the Canadian Flower class corvetteHMCS Algoma.[3]Edison '​s commanding officer, Commander Albert C. Murdaugh, USN, was the senior officer of the escort group.[3] The escort group had never operated together before.[4]Bernadou had been modified for long range escort work by replacing the fourth boiler and stack with an extra fuel tank.[5]Toward carried a High-frequency direction finding (HF/DF) set, and Nicholson had the only functional radar.[6]Lea carried a British ASV aircraft radar with fixed antennae, but the coaxial cable to the antennae was repeatedly shorted by salt water spray.[7]Edison had no depth charge throwers, and was limited to a linear pattern rolled off the stern.[8] The American ships did not have enough binoculars. Bernadou had a 7x50 pair for the officer of the deck and a 6x30 pair for the junior officer of the deck but there were none for the lookouts.[9]

U-155 found and reported the convoy on 21 February.[10]Toward obtained a bearing on the contact report, and Lea searched the bearing unsuccessfully at dusk.[11]U-155 approached the port quarter of the convoy in the pre-dawn hours of 22 February and torpedoed the British tanker Adellen and Norwegian freighter Sama.[11][12] Both ships sank quickly.[11]Algoma rescued eleven of Adellens crew of 31 while Nicholson and Toward found 20 survivors from Samas crew of 50.[11][12]U-155 crash-dived to avoid Bernadou, but the destroyer never saw the U-boat.[11]U-155 made another emergency dive while shadowing the convoy at 1042 hrs, but Edison did not detect the U-boat. U-587, U-69 and U-558 found the convoy on 23 February.

U-558 approached the convoy at 2120, but repeatedly turned away to avoid Bernadou '​s patrols until a squall provided cover at midnight. U-558 torpedoed the Norwegian tanker Inverarder at 0045 hrs on 24 February.[13][12] The tanker sank slowly and Toward rescued all 42 of the crew. U-558 approached again at 0230 hrs and fired a single torpedo at Edison.[13] The torpedo missed, and Edison was unaware it had been fired at.[13]U-558 torpedoed the Norwegian tanker Eidanger at 0255 hrs.[13]U-558 reloaded and at 0550 hrs torpedoed the British tankers Anadara and Finnanger, and the British freighter White Crest.[14][12] All three ships straggled and were sunk. Later that morning, the convoy commodore sent a signal to the escort commander regarding the performance of U-558: "That chap must be one of their best ones. I do hope you have done him in."[15]

U-158 found the convoy at 0425 hrs on 24 February and torpedoed the British tanker Empire Celt.[13]Empire Celt was using the Admiralty Net Defence system, streaming a strong steel net from 50-foot (15 m) booms along either side of the ship.[16] One torpedo broke through the net and hit amidships.[17]Empire Celt later broke in half, but a tug from Newfoundland rescued 31 from the crew of 37.[17][18]

As U-558 was torpedoing ships on the starboard side of the convoy, U-158 approached the port side and torpedoed British tanker Diloma at 0635 hrs.[19]Diloma was the only one of the torpedoed ships to successfully reach Halifax.[18] Both U-158 and U-558 dived to avoid being seen in the early daylight.[20]U-558 found and sank the Eidanger, drifting and abandoned astern of the convoy, with gunfire and a torpedo.[20] All of Eidangers crew had been rescued.[12]Lea investigated a DF bearing from Toward at 1515 and spotted U-558 20 miles astern of the convoy at 1707 hrs. Lea dropped eight depth charges at 1746 hrs, and then surprised the U-boat on the surface at 1813 and dropped 14 depth charges at 1847 hrs. U-558 was undamaged.[21]

Nicholson investigated a DF bearing from Toward and sighted U-158 at 1323. U-158 dived and evaded Nicholson. Nicholson then slowed to listen. U-158 surfaced at 1550 and was surprised to find Nicholson waiting 1500 metres away. U-158 crashed-dived before Nicholson saw the U-boat. U-158 surfaced again at 1817 and was surprised to find Edison 2,000 yards (1,800 m) away. U-158 again avoided detection by crash-diving. Edison finally spotted U-158 making another convoy approach at 2008 and dropped 25 depth charges over the following six hours. U-158 was undamaged, but had been prevented from making further attacks on the convoy.[21]